Simple formula
DTR equals time from first crack to drop divided by total roast time, multiplied by 100.
Home roasting guide
Development time ratio calculator for coffee roasting
Development time ratio compares time after first crack to total roast time.
Built into saved roast profiles
Coffee Roasting Timer calculates DTR automatically when first crack and drop are marked.
Use it with taste, not alone
DTR is a guide, not a guarantee. Pair it with drop temperature, RoR, weight loss, and tasting notes.
Questions
Common questions
How do I calculate DTR?
Subtract first crack time from drop time, divide that result by total roast time, then multiply by 100.
Is higher DTR always better?
No. Too much development can flatten acidity or create roast-heavy flavors. Use DTR as one signal in context.